Fatal car crashes involving pot use have tripled in U.S., study finds

(HealthDay News) -- The legalization of marijuana is an idea that is gaining momentum in the United States, but there may be a dark side to pot becoming more commonplace, a new study suggests.

Fatal crashes involving marijuana use tripled during the previous decade, fueling some of the overall increase in drugged-driving traffic deaths, researchers from Columbia University's Mailman School of Public Health report.

"Currently, one of nine drivers involved in fatal crashes would test positive for marijuana," said co-author Dr. Guohua Li, director of the Center for Injury Epidemiology and Prevention atColumbia. "If this trend continues, in five or six years non-alcohol drugs will overtake alcohol to become the most common substance involved in deaths related to impaired driving."

The research team drew its conclusions from crash statistics from six states that routinely perform toxicology tests on drivers involved in fatal car wrecks -- California, Hawaii, Illinois, New Hampshire, Rhode Island and West Virginia. The statistics included more than 23,500 drivers who died within one hour of a crash between 1999 and 2010.

Alcohol contributed to about the same percentage of traffic fatalities throughout the decade, about 40 percent, Li said.

But drugs played an increasingly prevalent role in fatal crashes, the researchers found. Drugged driving accounted for more than 28 percent of traffic deaths in 2010, up from more than 16 percent in 1999.

Marijuana proved to be the main drug involved in the increase, contributing to 12 percent of 2010 crashes compared with 4 percent in 1999.